[1] Field of the Invention
The present invention relates to a cyclically liquid feeding apparatus configured to feed liquid for cooling circularly to a load and to cool the load and, more specifically, to a cyclically liquid feeding apparatus configured to cool the load using two types of liquid having different liquid temperatures.
[2] Description of the Related Art
For example, in various manufacturing apparatuses such as semiconductor manufacturing apparatuses and liquid crystal manufacturing apparatuses, in order to cool the apparatuses (load) which generates heat and maintain the temperature constant, liquid for cooling is cyclically fed from the cyclically liquid feeding apparatus and cool the load. In this case, as disclosed in Patent Documents, Japanese Unexamined Patent Application Publication Nos. 2009-293867, 2009-287865, and 2008-292026, in order to control the temperature according to the calorific power of the load with a high degree of accuracy, preparing two types of liquid having different liquid temperatures and selectively feeding liquid having a liquid temperature suitable for cooling the load by mixing means including a plurality of three-way valves or the like, or feeding the same to the load in a state in which the liquid is brought into a liquid temperature suitable for cooling the load by mixing the two-types of liquid is also performed.
In examples disclosed in Patent Documents JP2009-293867A and JP2009-287865A described above, a heat source tank (high-temperature tank) storing high-temperature liquid therein, a cold source tank (low-temperature tank) storing a low-temperature liquid therein, and mixing means including a plurality of three-way valves or the like are provided, and liquid in the heat source tank or the cold source tank is fed to the load by a suitable amount using the mixing means. In the example in the related art disclosed in Patent Document JP2008-292026A, almost the same operations are performed.
However, in the related art, since the high-temperature tank and the low-temperature tank are installed at different positions separated from each other, the structure is complicated and cost is increased because not only the two tanks occupy a wide space of installation and hence the size of the apparatus is increased, but also heat-insulating processes such as condensation prevention or heat-radiation prevention should be worked respectively on each tank.
Also, when feeding the liquid to the load from the two tanks, the liquid moves between the two tanks in association with a switching operation of the mixing means, so that the liquid levels of the liquid in the two tanks vary significantly and hence becomes unbalanced, which may cause a trouble in temperature adjustment of the liquid in each of the tanks. Therefore, in Patent Document JP2008-292026A, a reserve tank is provided to absorb an increase and a decrease of the liquid in the cooling-side (low-temperature) tank and the heating-side (high-temperature) tank. However, the space for installing the reserve tank is additionally increased and, in addition, when liquid which is not controlled in temperature from the reserve tank flowed into the cooling-side tank and the heating-side tank, the temperature adjustment of liquid in the both tanks becomes further difficult.